1. Field of the Invention
The present invention relates to an engine generator composed of an engine and an engine-driven generator, and particularly to an engine generator which cools the interior thereof by an engine-driven cooling fan.
2. Description of the Related Prior Art
An engine-driven generator accommodated within a box-like housing for the generation of electricity is widely used as a power source at road construction sites, in street stalls, or for outdoor leisure. Japanese Patent Application Laid-open Publication No. 58-197415 and No. 58-197417 disclose such an engine generator. Here, an engine, an inner-rotor type generator, a muffler and others are accommodated in a main housing. The rotor of the generator is rotated by a crankshaft of the engine to generate an electromotive force on the side of the stator. A cooling fan is interposed between the engine and the generator so that it is rotated with the crankshaft for introducing cooling air into the main housing, thereby cooling the engine and the generator.
The cooling fan and the generator in this engine generator are further covered by a front housing and a rear housing, respectively, within the main housing. The front housing is attached to a side of an engine cover accommodating the engine therein and accommodates the cooling fan. The rear housing is mounted to the outer side of the front housing opposite to the engine, with the stator being fixedly interposed therebetween. The crankshaft is rotatably supported at an outer end of the rear housing.
When starting the engine by a recoil starter, the crankshaft starts to rotate, whereby the rotor rotates in the vicinity of the stator and electricity is generated. The cooling fan is at the same time rotated so that air is introduced into the main housing from the outside to cool the interior of the engine generator.
Japanese Patent Application Laid-open Publication No. 11-36880 is directed to an improvement in cooling efficiency of such an air-cooled engine generator which uses a cooling fan. FIG. 6 is a side view with a partial cross section illustrating the generator and the vicinity thereof in the engine generator according to this publication.
A generator 51, an engine 52, and a muffler (not shown) are arranged in this order within a housing (not shown), these being enclosed in a duct 53 and a fan cover 54. The generator 51 is of an outer-rotor type, its stator 55 being fixed to the engine 52. An outer rotor 57 coupled to a crankshaft 56 is disposed on the outside of the stator 55. A cooling fan 58 is mounted to an outer side of the outer rotor 57, to be driven to rotate with the crankshaft 56 for introducing cooling air 59.
The cooling air 59 first cools the generator 51 of which temperature is relatively low, and further cools the engine 52 and the muffler having a higher temperature sequentially, after which it is discharged to the outside. In this way, the engine generator of this disclosure is intentionally capable of efficiently cooling the interior of the generator 51, as well as it allows itself to be made compact by the use of the outer-rotor type generator.
While the engine generator disclosed in Japanese Patent Application Laid-open Publication No. Hei. 11-36880 offers an improvement in the cooling efficiency of the generator and a reduction in size, replacement of the stator 55 entails a complicated operation of disassembling some components. That is, after removing the fan cover 54, the cooling fan 58 and the outer rotor 57 must be dismounted. Thus the maintenance of the apparatus imposes demanding work because of the internal structure which does not allow the stator to be readily replaced.
The engine generator disclosed in the above-mentioned Japanese Patent Application Laid-open Publication No.58-197415 or No.58-197417 has a structure wherein the stator is interposed between the front housing and the rear housing. Accordingly, the stator can be replaced simply by removing the rear housing. On the other hand, the generator of this type is inherently long in its axial direction, because of which a reduction in size of the apparatus is hard to achieve. Moreover, the number of components are inevitably increased and so are the number of assembling steps, because the inner housing is composed of two separate parts.
An object of the present invention is to provide a small, light-weight engine generator which allows itself to be readily disassembled and assembled for easy maintenance.
An engine generator according to the present invention includes an engine, a generator having a rotor and a stator and driven by the engine, a cooling fan driven by the engine, and a fan cover for enclosing the cooling fan therein. In this construction, the rotor and the stator are accommodated within the fan cover.
According to the invention, in an engine generator including an engine, a cooling fan, and a generator, the rotor and the stator are accommodated within a single fan cover, whereby the number of components is reduced and water-proof performance is improved.
The stator may be mounted to the fan cover, so that the stator can be separated from the generator simply by removing the fan cover. As a result, the stator can be replaced without removing other components, whereby maintenance is facilitated and the number of working steps is reduced.
The cooling fan may be disposed between the engine and the generator in the engine generator according to the invention. Further, the generator may be an inner-rotor type generator, or alternatively, it may be an outer-rotor type generator.